AIM: To compare the clinical effectiveness of using multifocal defocus spectacle lenses, orthokeratology lenses, and single-vision spectacle lenses in patients with myopia and small-angle intermittent exotropia.

METHODS: This retrospective study included 150 patients aged 8-15 years with basic intermittent exotropia, strabismus of -10^△ to -20^△ prism diopters(D)(block lenses), and spherical equivalents of -1.00 to -5.50 D, who visited our hospital from June 2021 to September 2022. They were selected and divided into three groups on a voluntary basis: the HAL group(50 patients with multifocal myopia defocus spectacle lenses), the OK lens group(50 patients with nighttime orthokeratology lenses), and the SVL group(50 patients with regular single-vision spectacle lenses). After wearing the lenses consistently, changes in axial length, prism diopters with the naked eye and lenses(prism at 33 cm), positive fusional vergence of blurred points, and near stereopsis were observed and compared among groups before intervention and after 1 a. The Newcastle control score(NCS)was used to evaluate the eye position control ability of the patients in the three groups.

RESULTS: Before the intervention, the axial lengths of the HAL, OK lens, and SVL groups were 24.83±0.91, 24.93±0.97, and 24.98±0.68 mm, respectively(P>0.05). After 1 a, the axial lengths of the three groups were 25.02±0.90, 25.18±0.97, and 25.45±0.65, respectively(P<0.05). Compared with an increase of 0.47±0.30 mm in the SVL group after 1 a, the axial length of the HAL and OK lens groups increased by 0.19±0.06 and 0.25±0.21 mm, respectively(both P<0.05). Before intervention, the prism diopters of the HAL, OK lens, and SVL groups measured using the prism were -15.00^△±3.12^△, -14.34^△±3.00^△ and -14.06^△±3.22^△, respectively. After 1 a, the prism diopters of the three groups with lenses were -9.34^△±3.84^△, -18.42^△±4.41^△, and -19.58^△±5.21^△, respectively, which increased by 5.66^△±2.13^△, -4.08^△±3.34^△, and -5.52^△±3.70^△, respectively, compared with the preintervention values(P<0.05). Before intervention, the near stereopsis in the HAL, OK lens, and SVL groups were 89.20″±54.65″, 93.00″±52.54″, and 88.40″±55.31″, respectively(P>0.05). After 1 year, near stereopsis in the groups were 76.00″±20.40″, 81.20″±18.91″, and 100.60″±51.41″, respectively(P<0.05). The positive fusional vergence(fuzzy point)of the three groups was 15.04±1.97, 15.14±1.67, and 14.62±1.47, respectively, before intervention(P>0.05), and it was 17.10±2.02, 13.12±1.41, and 13.26±2.45, respectively, after 1 a(P<0.05). In addition, the eye position control in the HAL group was significantly better than that in the OK lens and SVL groups after wearing lenses for 1 a(P<0.05).

CONCLUSION: For patients with myopia and small-angle intermittent exotropia, wearing HAL can effectively control changes in strabismus and axial length compared with OK lenses and SVL, particularly for better control of strabismus, whereas wearing OK lenses or SVL would result in exotropic drifts. Stereopsis and positive fusional vergence were significantly improved in the HAL group.